This paper examines the hypothetical links between the languages of Japan and the languages of ASEAN countries and beyond. The common belief is that the Japanese languages are excluded from the ASEAN languages, but this paper attempts to hypothesize that the Ainu language of Japan belongs to the Austronesian stocks. Therefore several hypotheses are proposed to account for the possible links between the Ainu and the Japanese language and the languages of ASEAN countries and beyond. Basically there are two routes in which the languages of Japan received the influence in the early stage of developments. There is the northern route, which originates from the Altaic source and the southern route, from the Southeast Asian languages mainly the Austronesian language family. It is concluded that the languages of Japan received the influence from both the northern and southern routes plus some other countries.